The present invention relates generally to the field of heart rate monitoring devices and, more specifically, heart rate monitoring devices designed to monitor the heart rate of a newborn infant.
Currently, there are few methods of capturing the heart rate.
The first few minutes of life after birth is a critical time when dramatic physiologic changes take place to prepare an infant for the outside world. Often, some term and many premature neonates are born with complications that require immediate resuscitation to survive. The neonate heart rate is one of the key physiologic metrics doctors use for determining whether or not the resuscitation effort is working. Because the infant's heart rate is so important, an accurate, instantaneous representation of the heart rate can be crucial. Current methods require manual palpation of the pulsating umbilical cord or listening to (auscultation) with a stethoscope for heart beats, both of which are prone to inaccuracy and human error particularly in situations of high stress and in the presence of external stimuli or noises. Furthermore, these methods complicate the delivery room working area by increasing the number of bodies. Conventional pulse oximetry and electro-cardiograms also suffer from disadvantages due to respective signal delay (between 1 and 3 minutes) or difficulty with application. A device that can automatically capture the neonate heart rate immediately and accurately to the resuscitation team after birth and provide real time audio and visual feedback, could improve the quality of resuscitation offered and ensure that critical time sensitive decisions are made.
Current delivery room practices are not consistently accurate for the monitoring of the newborn heart rate. Most newborns are assessed at birth for a normal heart rate using one of three different methods. The first and simplest is the palpation of the umbilical cord with the hand. Manual palpation of the umbilical cord requires medical team members to sense the pulse and communicate it, using their fingers in a fashion similar to a metronome. Manual palpation requires significant clinical experience, but even then, experienced professionals are prone to critical errors.
The second method is auscultation. While auscultation is typically a good method for hearing heart sounds, the delivery room environment is often prone to excessive external stimuli and noises that can distract the listener from hearing the heart beats. The most common of these errors is either a miscount, where faint heartbeats are not sensed and therefore not relayed to the attending medical team, or double counts, where the atrial and ventricular systoles are counted as individual heartbeats rather than part of the same beat. It has been observed in some cases, using video recording of delivery room resuscitation, that a heart rate readout from a delivery room team member is not consistent with the simultaneous oxygen saturation or ECG monitor.
The third method of monitoring heart rate, which is less commonly used than the first two, is pulse oximetry. The advantage of pulse oximetry is that it is noninvasive and extremely accurate, providing information not only on heart rate, but blood oxygenation as well. Unfortunately, pulse oximetry devices can sometimes require 2-3 minutes of initial data collection to establish a patient's baseline, creating a “blackout window” during which they are ineffective. This has been most frequent in smaller preterm infants, which is disadvantageous since they are generally a sicker patient group. Therefore, while patients in stable condition or under observation are typically not hampered by this minor inconvenience, in neonates that are preterm and/or in respiratory distress or with other complications, a two minute “black window” can be a significant disadvantage.
Existing electrocardiographic technology is not easily suited for placement into the delivery room. The most reliable detection of heart rate is usually the placement of chest electrodes attached to an electrocardiogram (ECG) machine but two factors make it challenging to easily incorporate this. The first is the sticking of electrodes onto a newborn's skin. Freshly born infants have skin that is wet and often covered with vernix. Both conditions can make sticking of electrodes difficult. The second problem is the bulkiness of typical ECG machines and cumbersomeness of the leads. Most delivery rooms do not have the space or capacity to provide machines in all the different delivery areas such as labor rooms, operating rooms, and resuscitation rooms. A portable device for accurately measuring a neonates heart rate would be helpful in emergency situations where other team members are scarce and when such a device could be carried readily in transport.